Wpływ metody sterowania na stabilność parametrów chromatycznych diod LED

Main advantages of semiconductor light sources are high luminous efficacy and possibility of controlling the luminous flux over a very wide range. However, the quality of such lighting, in many cases, was noticeably poorer than that offered by classical solutions making use of fluorescent or incandescent lamps. Technological advances have made possible production of LEDs that emit light, which is, according to their manufacturers, energy saving and eyes-friendly. For the best LEDs the Colour Rendering Index (CRI) exceeds 90. Nevertheless, it is worth mentioning that high values of CRI and colour temperature stability are only obtained under predetermined measurement conditions. Real operating conditions may considerably differ from the reference ones and, therefore, cause deterioration of the most important parameters of LED lighting. In our work we have examined and described how the method of dimming, i.e. light intensity control (variation of constant current IF or PWM), influences chromatic parameters of LEDs used in lighting technology.